Intercostal tubes have been heretofore made with squared ends. When such a tube is inserted between the ribs, it is very difficult to insert because of the squared end and the large area that must be inserted. Accordingly, the end to be inserted is usually squeezed or compressed transversely to make the tube narrower to require less of an incision in order to pass between the ribs. But this squeezing increases the vertical dimension of the tube and thereby requires a larger opening in the area between the ribs, which can cause the patient pain. It is also recognized that some tubes for other uses have been made with sloping ends but not of the present material and not with the present type of end that can be inserted between the ribs. An example of this is the Sanders U.S. Pat. No. 2,458,305. Also intravascular catheters have been made with trocars wherein the trocar has a sloping end. But in that case, the trocar is usually of metal and it is of a very small size designed to enter a vein or the like part of the human body. Thus it does not have the problem of being flexible and yet being stiff enough to be inserted between the ribs, or of being widened upon being squeezed.